The invention relates to an infrared radiator for an infrared drying unit with a radiator housing that is subdivided internally by a gas-pervious burner plate into a distributing compartment for the gas/air mixture and into a combustion compartment. A large portion of the energy contained in the combustion gases is convectively transmitted in the combustion compartment to a solid body that gives this energy up as infrared radiation at its front side. The radiator has a back housing wall mounted on a mixing tube through which an gas/air mixture is supplied to the distributing compartment, the mixing tube having on its end remote from the radiator housing a gas nozzle with a gas feed, being connected to an air feed, and being fixed on a frame of the drying unit.
Such infrared radiators are as is known installed in dryer systems that serve for drying web-like materials, for example paper or cardboard webs. Depending on the width of the web to be dried and the desired heat capacity, the necessary number of radiators are assembled in one or more rows to a drying unit, the individual radiators being mounted immediately adjacent one another. Such an infrared radiator is described in EP 0,128,202.
Gas-heated infrared radiators are subject to wear in use so that it is necessary to replace them after a service life of about two to four years. In addition they must be serviced as a rule once or twice a year in order to check whether the gas nozzle in the mixing tube or the radiator itself is dirty. Switching and servicing the known radiators is very time intensive since several steps must be carried out to remove the radiator housing and clean the nozzles, carried out when the dryer is cooled off and is thus not in use. This creates down times for the equipment in which the drying unit is integrated, for example a coating system for paper or cardboard webs.
It is therefore an object of the invention to improve on this type of infrared radiator and/or mount therefor so that it can be removed as quickly as possible from and reinstalled back into an infrared drying unit.
This object is attained according to the invention in that the radiator housing is connected on its rear side with the frame via releasable fastening means which are manually releasable from the front side.
The radiator can thus be rapidly removed and again reinstalled, working from the easily accessible front side. Servicing parts of the radiator can be done outside the equipment under no particular time constraints.
In one embodiment, the radiator housing is bolted on the mixing tube via screws that can be tightened or loosened from the radiating front side of the radiator. Preferably the screws are so constructed and screwed in so far that their heads are in the cooler distributing compartment for the gas/air mixture behind the burner plate and not in the hot combustion compartment in front of the burner plate. The burner plate thus has corresponding bores through which the screw heads can be reached with a tool. If a metal mesh overlies the radiating surface, it is either only clipped in place so it is easily removed or it also has aligned bores.
The radiator is particularly advantageous and easy to remove when equipped with a speed coupling that is releasable by pushing or pulling on the front side, that is by a force parallel to the axis of the mixing tube. The speed coupling can be made of a standard coupling mechanism and includes as coupling parts a sleeve-shaped holding part and an insert part that can be coupled with each other, the coupling force being exerted by spring elements that free the insert part when pushed or pulled.
The speed coupling is between the housing back wall and the mixing tube, between the gas-supply line and the gas nozzle, or inside the mixing tube. The gas nozzle is preferably fixed in the mixing tube. In the particularly advantageous embodiment, the gas nozzle is removable from the drying unit with the mixing tube and the radiator housing fixed thereto and can thus be serviced outside the equipment. When the gas nozzle is bolted into one coupling part of the speed coupling, it is accessible after opening of the speed coupling and can simply be screwed out.
A preferred and even particularly advantageous embodiments of an infrared radiator is secured in a solid and gas-tight manner on the frame and that is removable by pressure on the front side of the radiator housing.
The infrared radiator has a socket part, an insert part at least partially slidable against the force of a spring into the socket part, and a latching mechanism with a latch element and a complementary socket element. The latching element is fixed on one of the coupling parts, moves on fitting of the one coupling part into the socket element on the other coupling part, and is mounted on a pivotal mechanism that is actuated on movement of the insert part of the speed coupling against the socket part and alternately moves the latch element into a latch position holding the coupling parts together or an unlatched position in which the coupling parts can be separated from each other.